Vision changes have been found in approximately 20% of astronauts returning from lengthy International Space Station missions. These changes are thought to be a result of the increase in intracranial pressure brought on by microgravity's characteristic headward fluid shift. Characterized as visual impairment/intracranial pressure, the changes include papilledema (swelling of the optic nerve), globe flattening, choroidal folds, "cotton wool" spots, thickening of the optic nerve, and decreased visual acuity. Since the exact cause of the impairment is undetermined and the long-term consequences remain unknown, Visual Impairment/Intracranial Pressure has been deemed a new human spaceflight risk for astronauts.
Scientists at USRA's Division of Space Life Sciences, who have extensive experience in high altitude medicine as well as medicine in isolated and confined environments, were selected by NASA to lead a research project to investigate the onset of visual impairment/intracranial pressure (VIIP) of space flight. Leading medical and scientific experts have developed a research plan to better understand the etiology and identify countermeasures to mitigate the VIIP risk.
Others from USRA's Division of Space Life Sciences have been recruited to study the problem from different angles. Scientists are studying the effects of radiation and lunar dust on rodent retinas, biochemical markers to determine if the folate- and vitamin B-12-dependent 1-carbon metabolic pathway is altered in the individuals exhibiting visual changes, and are computationally modeling and simulating Visual Impairment and Intracranial Pressure.